Multifocal ophthalmic lens

Abstract

An improved opthalmic lens is disclosed which has a plurality of alternating power zones with a continuously varying power within each zone, as well as in transition from one zone to another. In other words, a plurality of concentric zones (at least two) are provided in which the variation from far to near vision correction is continuous, i.e., from near correction focal power to far correction focal power, then back to near, and again back to far, or vice versa. This change is continuous (progressive), without any abrupt correction changes, or "edges". Two versions of the invention are disclosed. In the first version continuous, alternating power variation is accomplished by a continuously alternating power variation is accomplished by a continuously changing curvature of the lens posterior surface, thereby altering the angle of impact of light rays on the eye. In the second version continuous, alternating power variation is accomplished by creating non-homogeneous surface characteristics having refractive material indexes which continuously vary in the lens radial direction (out from the optical axis).

I claim: 
     
       1. A multifocal ophthalmic lens for providing variable vision correction power, said lens being adapted for implantation in an eye or to be carried on a surface of the eye, said lens having a central zone providing a predetermined vision correction power and a plurality of annular regions circumscribing the central zone, a first of the annular regions having progressive vision correction powers which vary progressively in a radial outward direction from said predetermined vision correction power at said central zone to one of near and far vision correction powers, said one vision correction power being different from said predetermined vision correction power, a second of the annular regions having the other of said near and far vision correction powers and a third of said annular regions having progressive vision correction powers varying progressively between the far and near vision correction powers, said third region circumscribing the first region and the second region circumscribing said third region. 
     
     
       2. A lens as defined in claim 1 wherein said annular regions are concentric. 
     
     
       3. A lens as defined in claim 1 wherein said lens is an intraocular lens adapted for implantation in the eye. 
     
     
       4. A multifocal ophthalmic lens for providing variable vision correction power, said lens being adapted for implantation in an eye or to be carried on a surface of the eye, said lens having a first region and a plurality of annular regions circumscribing the first region, said first region and at least one of the annular regions having a first vision correction power, another of said annular regions having a second vision correction power, said annular regions including an annular transition region extending between said first region and said another region, said one region circumscribing said another region, one of said first and second vision correction powers being a near vision correction power and the other of said first and second correction powers being a far vision correction power and said annular transition region having progressive vision correction powers which vary progressively between the near vision correction power and the far vision correction power, said annular regions including a second annular transition region which is between said another region and said one region, said second annular transition region including intermediate vision correction powers which are intermediate the near vision correction power and the far vision correction power and which provide vision correction for intermediate distances. 
     
     
       5. A multifocal intraocular lens for providing variable vision correction power adapted for implantation in an eye, said lens having a first region and a plurality of annular regions circumscribing the first region, said first region and at least one of the annular regions having a first vision correction power, another of said annular regions having a second vision correction power, said annular regions including first and second annular transition regions between said first region and said another annular region and between said another annular region and said one annular region, respectively, one of said first and second vision correction powers being greater than the other of said first and second vision correction powers and said first annular transition region having progressive vision correction powers which vary progressively from the first vision correction power to the second vision correction power and the second annular transition region having progressive vision correction powers which vary progressively from the second vision correction power to the first vision correction power. 
     
     
       6. A lens as defined in claim 5 wherein all of said regions are concentric. 
     
     
       7. A lens as defined in claim 5 wherein said first vision correction power is far vision correction power and said second vision correction power is near vision correction power. 
     
     
       8. A lens as defined in claim 5 wherein the second vision correction power is greater than the first vision correction power. 
     
     
       9. A multifocal ophthalmic lens for providing variable vision correction power, said lens being adapted for implantation in an eye or to be carried on a surface of the eye, said lens having a central zone for providing a predetermined vision correction power and a plurality of annular regions circumscribing the central zone, a first of the annular regions having a first vision correction power, a second of the annular regions having progressive vision correction powers varying progressively in a radial outward direction between the predetermined vision correction power and the first correction power, a third of the annular regions having a second vision correction power and a fourth of said annular regions having progressive vision correction powers varying progressively in a radial outward direction between the first and second vision correction powers, said third region circumscribing the fourth region, the fourth region circumscribing said first region and the first region circumscribing the second region, said predetermined and second vision correction powers both being less than or both being greater than the first vision correction power. 
     
     
       10. A lens as defined in claim 9 wherein the predetermined vision correction power of the central zone extends throughout the central zone.